Sciencemadness Discussion Board


Romix - 26-6-2015 at 18:26

I heated up pure crystalline paracetamol, and it melted.
First time I melted it, it wos see through.
Paracetamol changed colour to dark brown on fifth melt.
It's insoluble in cold water, soluble if heated, crystallises to dark crystals.

What is it?

I dissolved it in NaOH now to clean tube walls, still brown...

[Edited on 27-6-2015 by Romix]

[Edited on 27-6-2015 by Romix]

Pumukli - 27-6-2015 at 03:01

It is still paracetamol, but contains increasing ammounts of oxidation byproducts from the repeated melting. You may purify it by adding activated charcoal before recrystallization, though don't expect too much pure product, even less, if you continue re-melting. :-)

Schizophrenic - 27-6-2015 at 06:15

azobenzene is the red compound in the case of the reduction of nitrobenzene to aniline, this product is the result of the reaction of aniline with nitrosobenzene. The last product is formed by the oxidation of aniline with oxygen, I think it's a similar byproduct.